Automatic feed-controlling system for mechanical stokers



Nov. 15, 1927.

D. J. M LEAN AUTOMATIC FEED CONTROLLING SYSTEM FOR Filed July 29. 1920 MECHANICAL STOKERS 4 Sheets-Sheef 0006.4 *7 J lV/KZEHN war, 1

- HT 'ysI Nov. 15, 1927. 1,649,537

D. J. M LEAN AUTOMATIC FEED CONTROLLING SYSTEM FOR MECHANICAL STOKERS Filed July '29. 1920 4 Sheets-Sheet 2 I NVENTOR 00001.17; J Mac 1 17 Nov. 15,1927? 1,649.53?

D. J. M LEAN AUTOMATI C FEED CONTROLLING SYSTEM FOR MECHANICAL STOKERS Filed July 29, 1920 4 Sheets-Sheet 3 Baum/7s Jim/101mm.

' Nov. 15, 1927.

D. J. M cLEAN AUTOMATIC FEED CONTROLLING SYSTEM FOR MEcnANI cAL STOKERS Filed July 29, 1920 4 Sheets-Sheet 4 W W H,

I N VE N TOR.

Dal/aims PatentedN ov. 15 1 927.

UNITED STATES DOUGLAS JERROLD IYIACLE A N, OF WEST HILL, ONTARIO, CANADA.

AUTOMATIC FEED-CONTROLLING SYSTEM FOR MECHANICAL STOKERS.

Application filed July 29,

My invention relates to automatic feed controlling systems for mechanical stokers and the objects of the invention are z-firstly, to reduce the steam consumption of the stoker to a minimum; secondly, to eliminate toa great extent the loss due to condensation of steam in the passagewaysbetween the stoker valves and the cylinder of the Stoker; thirdly, to provide a controlling system which will be very flexible and in which the supply of coal delivered by the stoker to the furnace will be automatically governed by the rise and fall of the boiler preszure; tourthly, to provide a positive mechanical adjustment whereby the ratio of coal supply to air supply may be adjusted, to give perfect combustion, independently of the above. automatic control; and lastly to provide in addition to the above, manually operated means for actuating the timing valve whereby the stoker may be made toi'eed any desired number of charges of coal independently of the automatic operation of same.

My invention consists of a mechanical stoker having the usual steam cylinder and ram operating piston therein, a valve chest formed integrally with the stolter cylinder and having suitably disposed ports leading to each endof the stoker cylinder, amain stoker valve having freedom of reciproca tion within the valve chest, inlet and exhaust pipes communicating with the valve chest, a timing-valve, steam inlet and erhaust pipes communicating with the timing valve and a steam pipe leading from the timing valve to the main valve for operating the latter, an engine, a pressure regulating valve in the steam line to the engine for controlling the speed of the same in relation to the variations in the boiler pressure, a blower fan driven from the engine, a ratchet drive for the timing valve, the timing valve 1920. Serial No. 398,791.

valye chest showing the stoker piston and mam valve in one operative position.

Fig. 3 IS a similar view to ldig. Zshowing the stoker piston and, main valve in the operative position at the opposite ends of their strokes tothat shown in Fig. 2.

Fig. t is a similar view to 1 i a modified construction.

Fig. 5 is a longitudinal vertical section olithe timing valve showing the steam pipes communicating therewith.

Fig. 6 is a section on the. line 6.6 of Fig.5.

Fig. 7 is an end elevation of the adjustableratehet drive for-the timing valve:

Fig. 8' is asection on the line 88 of Fig. 7.

Figure 9 is a detail tron between the valve mechanism of the de vice and the timing mechanism.

Figure 10 is a cross sectional view of a conventional type of pressure regulating valve.

In the drawings like characters of reference indicate similar parts in thedifi'erent vlews.

j 1 is the boiler casing. 2 is an engine hav mg the flywheel 3. i is a blower fan mounted on the shaft- 5 and driven by the belt 6 and pulley 7. 8 and 9 are gears suitably mounted and supported by the boiler casing and constitute a speed reduction gear. 10 18 a pulley suitably connected to the gear 8 and is driven from the fan shaft 5 by the are mounted and has the squared outer end '22. 23 1s the mam steam pipe which is con nected to the valve chest at 2% and leads to the engine by the branch 25. 26is a pressure regulating valve. 127 is an engine exhaust pipe. 28 is a live steam pipe leading to the timing valve. 29 is a steam pipe leading from the timing valve to the main valve chestl i which enters at 31. The elvhaust pipe 27 is connected to the valve chest Fig. 2 showing view showing the rela- 14; at B3. 34:, 35, 36, 37, 38, 39 and 40 are ordinary shut off valves. alis the EiiSOliOl' piston suitably mounted in the cylinder 13. 42 is any suitable form of packing gland for the piston rod 43 which is ordinarily connected to fuel feeding ram.

The valve chest 1 1 has a cylindrical bore 44, one end of which is closed by the flanged cap 15 which has the inwardly extending sleeve 46 which fits into the bore 44: and forms a cylindrical portion 4:7 of reduced diameter. The end wall of the cap 45 is provided with the vent 18. 1

49 is a plate suitably closing the opposite end of the valve chest. 50 and 51 are circumferential grooves or recesses in the wall of the valve chest and 52 and 53 are ports leading from these grooves to the interior of the cylinder 13 adjacent to each end thereof. 54'and 55 are circumferentialrecessed portions at each end of the cylinder bore and 56 and 57 are grooves connecting them to the ports 52 and 53. The stoker main valve com prises the hollow piston 58to whichisconnected the opposed piston 59 by the rod 60. The piston 58 is open at its inner end at 61 and fits into the bore 14. The piston 59 isof smaller diameter and fits into the bore 17 of the sleeve 46. G2 are ports extending through the wall of the piston 58 and 63 is a peripheral groove in the outside of the piston which communicates with the ports 62. 61 is a peripheral recessed portion on the outside of the piston. 65 are piston rings. The

timing valve 15 which is illustrated in Figs. m

5 and 6 comprises the cup shaped casing 66 having the flanged portion 67 at its open end. The cover plate 68 closes this open end, being secured to the flange 67 by the bolts 69. The shaft 21 extends through a suitable stuffing be 70 in the closed end of the easing 66, aabearinsg being formed by the casing for the shaft at 71. The valve body 72 is rotatably mounted within the casing 66 and is provided at one end with the boss 73 which is recessed at 74. The end of the shaft 21 is formed into a male driving portion 75 which engages the recess 74:.

t will be seen that the shaft 21 is mounted to rotate the valve body 72. The steam pressure within the chamber 76 maintains the opposite end face of the valve body in engagement with the inner face of the Cover plate 68. 76 is an annular chamber formed within the casingGG between the closed end of the casing andthe valve body 72. The steam pressure in this chamber normally keeps the valve seated. The live steam pipe 28 communicates with this annular chamber at 77. 7 8 is a concentric recessed portion in the face of thevalv-e body 72 which is in contactwith the cover plate 68 and has the central pocket 80 formed by the wings 79. 81 is a port extending longitudinallv through the valve body. The cover plate 68 is proable ratchet drive 16 is mounted on the shaft 21 (see Figs. 7 and S). The ratchet gear 85 is keyed to the shaft 21 by the key 86 and has the bearing sleeves 87 and 88 formed integrally therewith. Theqpawl carrying plate 89 is rotatably mounted on the slcwe 87 and is provided with the int grally formed lug 90 which has the opposed faces 91 and 92. The two pawls 93 and 01 are rotatably mounted on the bolt 95 which is secured to the lug 90. The ratchet casing:

96 is rotatably mounted on the sleeves 81' and 88. the plate 97 constituting the rear end of said casing. casing so shaped as to form theare shapial cut away portion 99 having the end ilaccs 100 and 101. The index lever 102 is also rotatably mounted on the sleeve 87 outside the casing" 96; This lever 102 is provided with the lug 103 having the opposed faces 105i. and 105. The locking pin 106 is nmuutcd in the boss 107 formed on the lever 10:2. 1051 is a compression spring controlling said locking pin and 109 is a hand lmoh for withdrawing the pin as desired in making: an adjustment. The inner end 110 of the loch:- ing pin is adapted to register with and en gage any one of a series of index orifices 111 formed in the front face 98 of the casing,

thus locking the index lever 102' in any in sired position with respect to the ratchet casing. The orifices 111 are struck at equal radii and each orifice is numbered for com venience in setting. A peep hole 112 is provided in the lever 1.02 so that the nuuihcr of the orifice 111 at which the setting is desired may heaccurately seen. 1121 is a retaining: collar which is secured to the sleeve 87 by the set screws 11 1 and serve to hold the complete ratchet assembly in place on the shaft 21.

The operation of my system is as follows The general lay-out of the system will best i through the connecting rod 18 and this in turn operates the ratchet drive 16, and the timing valve 15, thus admitting steam to the valve chest 14 through the pipe Qilend operating the stoker main valve and stoltcr The front face 08 of: the

lee

piston and ram all as will be more fully described in detail hereinafter. j

The pressure regulating valve 26 is placed in the steam line to the engine and is set to maintain a desired boiler pressure Should the boiler pressure tall slightly below the desired point this valve opens allowing more steam to the engine and increasingits speed.

This results in increasing the speed of the fan which thus delivers more air to the furnace for combustion. At the same time the speed of the reduction gears incrases which increases the rate of oscillation of the ratchet arm 17 and consequently the rate of operation of the timing valve 15. This increases the speed of the stoker and the rate of de livery of coal to the furnace. It will thus be seen that as the boiler pressure falls the rate of combustion is increased which immediately raises the boiler pressure. 1

I1 the boiler pressure should rise above the desired point the regulating valve 26 will close and reduce the speed of the engine and the reverse of the above described operations will occur resulting in the lowering of the rate of combustion in the furnace and the consequent falling of the boiler pressure.

In addition to the above automatic control my adjustable ratchet permits the increasing or decreasing of the amount of coal fed through the stoker by adjusting the index lever 102 so that the pawls take a greater or lesser number of teeth on the ratchet gear at each stroke. In this way it is possible to properly proportion the amount of coal to the air supply. The timing valve may also be rotated by hand so that the stoker may be made to feed any desired number of charges of coal in this way independently of the control through the fan.

Having described the general operation of my system I will now describe in detail the operation ot the various parts comprising the system.

Considering the parts of the ratchet meche anisn'i in the positions shown in Fig. 7 and the connecting rod 18 to be moving upwardly, as the ratchet arm 17 moves up wardly the ratchet casing 96 will be oscillated in thedirection of the arrow. When the face 101 off the cut away portion 99 has engaged the face 91 of the lug 90 on the pawl carrying plate 89, further movement of the ratchet casing will rotate the pawl plate 89 and through the pawls which engage the teeth the ratchet gear 85 will be rotated. This in turn will rotate theshatt 21 and since this shaft drives the timing valve the latter will also be rotated.

On. the downward movement of the rod 18 and ratchet arm 17 the faces 101 and 91 separate and the pawls remain stationary until the index lever 102 comes into operation. This lever is locked to the ratchet casing by the pin 106 and therefore oscillates with said casing. As the downward movement of the arm 17 continues, the lug 103 of the index lever moves upwardly and when its face 104 has engaged the face 92 of the lug 90. on the pawl carrying. plate, further movement will move the plate 89 and with it the pawls backwardly over the teeth of the ratchet gear. Upon the following upward movement of the arm. 17 the same operations occur and the ratchet gear is again rotated, the extent through which it is moved in any one oscillation of the arm 17 corresponding to the number of ratchet teeth passed over by the pawls on their backward travel.

It will readily be seen that by adjusting the index lever 102 so that the pin 106 engages any desired one of the index orifices 111, the number of teeth passed over by the pawls and therefore the are through which the ratchet gear and timing valve are retated for one complete oscillation of the ratchet arm may be varied. By using the index orifice marked zero no movement whatever of the ratchet gear will result and the timing valve would not be operated at all whereas by using the index orifice marked eight the maximum movement of the valve will be produced as eight teeth will be passed over by the pawls.

Two pawls are provided with their points one half tooth apart so asto allow of finer adjustments of the index lever.

The operation of the timing valve and stoker main valve is as follows:

The live steam enters the annular chamber 7 6 (see Figs. 5 and 6) through the pipe 28. As the valve body 72 is rotated by the ratchet drive, for a portion of each revolution the port 81 registers with the port 82 sothat the live steam is delivered to the pipe,

29, this steam enters the main valve chest throughtheport 31 (see Fig. 3) and drives the Stoker main valve to the opposite end of the valve chest. In this position live steam entering the valve chest through the port 24 is allowed to pass into the interior of the hollow piston 58 through its open end 61 and through the ports 62 into the groove 50 of the valve chest and thence through the port 52 into the stoker cylinder 13 andforces the stoker piston 41 and the piston rod 43 outwardly withdrawing the At the same time the ram (not shown). steam isexhausted from the opposite side of the stoker piston and passes outwardly through the port 53, recessed portion 6 1 of the piston 58 to the exhaust port 33. The

path of the steam in this operation is as indicated by thearrows in Fig. 3.

The wings 7 9 of the recessedv portion of the valve body are so disposed that when the timing valve completes a certain part of a revolution the exhaust port 8 1 is brought into connnunication. with the port 82 allow- Fig. 2 the live steam enters the stoker cyl-.

inder through the port 53 and forces the stocker piston inwardly and with it the ram.

The steam is exhausted from behind the stoker piston through the port 52, recessed portion (it of the piston 58 and the groove 50 to theexliaust'portilil.

It will be seen that the piston 59 0f the main valve being oft less diameter than the piston 58, the unbalanced pressure exerted on the piston 58 will tend to force the valve into the position shown in Fig. 2 when the steam pressure is removed from the head of the piston 58, and that when the steam pressure acts upon the head of the piston 58 the main valve Wlll be forced in the reverse d1 rcction into the position shown in Fig. 3. This construct on ren dersit possible to operate the mam valve with a slngle pipe leading from the timing valve. A vent 48 is provided in the end wall of the valve chest be hind the piston 59.

It will be realized that the greater the number of ratchet teeth operated each stroke of the arm 17 the greater will be the are through which the timing valve will be rotated each stroke and consequently the stoker main valve will be operated more rapidly, which will in turn increase the rate of operation of the stoker piston and ram resulting in an increased rate of coal delivery to the furnace. i it 1 i i The end of theshatt 21 is squared to take a' crank handle orwrench whereby the timing valve may be rot-atecl'hand thus causing the stoker to feed any desired number of charges of coal by suchhand operation independently oi the automatic control above described.

The foregoing description has been confined to a type in which a single pipe only leads from the timing valve to the stoker main mlve but two pipes could be used as in the modified construction illustrated in Fig. 4. In this case the main valve chest is of the same diameter throughout. and both pistons of the main valve] are of the same diameter. The two pipes 29 and 30 lead respectively to the two ends of the valve chest and by providing two ports 82 in the timing valve the steam is alternately admitted to and exhausted from the portionsof the main valve chest at each end of the main valve and thus the valve is reciprocated as the timing valve rotates. The construction of the main valve,

valve chest and ports therein is exactly similar to that already described except that the two pistons 58 and 59 are of equal diameter, the valve chest is of constant diameter throughout and no vent is used, both end faces of the valve chest being entirely closed. The path of the steam inthis modified construction is shown in Fig. 4.

By my invention I place the main valve in a valve chest preferably formed integrally with the stoker cylinder, and the steam passages leading to the cylinder from the valve are very short. Further, the steam pipes leading from the timing valve to the main valve are very small and the displacement of the main valve being very little, the amount of steam required to operate it is also very small so that there is a very great saving in steam consumption by using such a timing valve to operate the main valve, rather than makingthe timing valve large enough to operate the Stoker directly. A further advantage in my system is that the timing valve and all operating levers and mechanism therefor can be placed at the side ot the boiler casing or in any other convenient location and there is no valve moving mechanism about the stoker cylinder to cause inconvenience. My main valve being constructed with short direct steam passages there is practically no loss due to condensation or loss in a clearance displacement.

I am also aware that a timing valve has been used to operate the main valve of a Stoker, in which the speed is controlled similar to'the action of a duplex steam pump which permits of a lag or pause between strokes, the speed of the strokes being regulated by the adjustment of a needle valve allowing the condensed water or steam to pass from a dash pot chamber, the strokes becoming more rapid as the opening of the needle valve is greater.

This is entirely dil'i'ereut.trom my ratchet operated timing valve which has a'delinite and fixed cycle or operation, being mechanimlly driven in direct ratio to the number of teeth taken by the pawls on the ratcl'iet gear and its speed is nn-ichanieally governed in direct ratio to speed of the tan through the speed reduction gear. The number bi ratchet teeth taken being governed by the setting ot'the index lever 102. By this adjustment it is possible to vary the amount of coal fed independently of the speed of the fan and thus the ratio of coal to air can be adjusted to give efficient combustion.

Many modifications may be made in my invention without departing from the spirit of the same or the scope of the claim and the forms shown are to be taken as illustrative and not in a limiting sense.

From the foregoing it will be seen that I have devised an automatic feed controlloo ling system for mechanical stokers which will allow of great flexibility in operation, will enable a very considerable economy in steam consumption to be effected and in which there will he no valve operating levers or moving parts located about the stoker cylinders.

\ Vh-at I claim as my invention is:

In a mechanical Stoker, the combination with the stoker cylinder and piston mounted therein, of a cylindrical valve chest, ports leading from the valve chestto each end of the stoker cylinder, circumferential grooves in the valve chest coinciding with the aforesaid ports, a hollow piston valve open at its inner end mounted within the valve chest, an opposed piston connected to the hollow piston, means for reciprocating the valve by fluid pressure, the hollow piston having ports therethrough and a peripheral recessed portion in its outer face, the valve chest provided with a main inlet port located between the opposed pistons and an exhaust port located to be at all times in commun1- cation with the peripheral recessed portion in the hollow piston, the ports in the hollow piston registering at one end of its stroke with one of the ports leading to the stoker cylinder and the recessed portion in the hollow piston uncovering separately the ports leading to the stoker cylinder at the corresponding ends of each stroke of the valve.

DOUGLAS J'ERROLD MAOLEAN. 

